Recently completed a 1.2L TDI install in a 2000 Honda Insight on Friday (17JUL09). The jury is still out on fuel mileage but 100 mpg doesn't seem out of the realm of possibility.
An Arduino was used to build a translator box that takes VW engine signals, formats them, then passes them along to the Honda Engine Control Unit (ECU). This allows the car to function like the original did.
Best wishes,
Jake
Take a look at www.redlightracing.org for build details. The first video of the car can be found at:
VW 1.2L TDI Powered Honda Insight - YouTube
The car to functions like the original did. The hybrid features of the car are fully functional as a result: VW 1.2L TDI Powered Honda Insight with Hybrid Functionality - YouTube
Best wishes,
Jake
impressive 
big thumbs up!!!
Extremely impressive :0)
Any ideas about making this PoC somehow commercial available? Like some kind of extremely heavy chipset modification? For Smart hybrids there are certain modifications available to reduce mpg, yet nothing as big as yours exchanging the motor..
Anyway - impressive work, keep us updated please :0)